Latex paint compositions used for coatings are typically made up of at least three components: binder, diluent, and pigments. In a latex paint, the binder is typically an emulsion polymer that forms a film as the paint dries. A diluent is typically a solvent that evaporates as the paint dries. A typical diluent in latex paint is water. Typical pigments include inorganic, organic, and carbon black. Additional ingredients may include coalescing aids, thickening aids, dispersing aids, defoamers, biocides, etc. to improve paint properties.
Pigments may be divided into two major categories, inorganic and organic pigments. Examples of inorganic pigments are various metal oxides such as C.I. Pigment Red 101, C.I. Pigment Yellow 42, C.I. Pigment Brown 6, C.I. Pigment White 4 and C.I. Pigment White 6. Examples of classes of organic pigments are the anthraquinone, azo, diketopyrrolopyrrole, dioxazine, indanthrone, indigo, isoindoline, isoindolinone, perylene, phthalocyanine, quinacridone, and quinophthalone classes. Carbon black, while containing carbon is not considered to be an organic pigment.
Organic pigments typically provide improved chromatic strength and brilliance of shade compared to inorganic pigments, but are generally less stable than inorganic pigments and tend to fade faster. Light, heat, humidity, and atmospheric pollutants, such as ozone, SO2, and NOX, are major factors that contribute to the fading of pigments.
Consequently, a significant need exists for new formulations of latex paints containing organic pigments which are less susceptible to fading due to light, heat, humidity, and atmospheric pollutants.